A belated welcome to HealingWell and the CFS forum!
Great reply snohare!
I agree that your fears about indescretions in Mexico are confusing you and maybe somewhat clouding your presentation of your case to your Drs. Although, there is one STD that I know about that could cause symptoms like you're experiencing, and I only know it by the name "herpes". If I'm not mistaken, there are a few different "varieties" of sexually transmitted herpes, but I couldn't name them. Just be sure your Dr has screened you for all of them. I think one of them does onset as early as a week after exposure, and does have symptoms very much like you're describing.
Also, as snohare mentioned, there would seem to be some chance you picked up an odd bug from something you ate or drank -- ever hear of "Montezuma's Revenge"? I'm not sure what organisms are involved, maybe it is giardia, I don't know. But it's quite common for people to get diarhea during or following a trip to Mexico. It is frequently said visitors should not drink the water when visiting there, but one can still have problems from food, as water is obviously used in preparing food, cooked or not.
Otherwise, from the perspective of CFS, it often begins much like you are describing, almost always following a period of heavy stress. Strange infectious symptoms, resembling or sometimes identical to EBV, rogue low-grade fevers and swollen glands, ulcers in mouth, sore throat, flu-like and otherwise bizarre, annoying symptoms; on top of overwhelming fatigue, all together they consititute serious illness.
It sounds to me like you became sick that same night, from something in the food or water. And unless your Dr gave you the specific antibiotic for the infecting organism, it may still be causing you some problems, keeping you weak, perhaps compromising your immune system and allowing all your other symptoms to manifest. Or maybe your body did heal and recover, only to be struck by either the herpes std or CFS. I'm not a Dr, so don't have the skills and abilities to diagnose, but it does seem that's what you need to focus on at this point. Once you have a diagnosis, you can begin to think about treatment.
If you have a Dr who is working with you, make sure you were screened for all the STDs, especially herpes. If the Dr says you're good, then you're good! To my knowledge, there's no controversy over, or subjective diagnostics regarding std. Find out if your Dr has seen or heard of the diagnostic criteria for CFS. If not, you can direct him to this info at the CDC website: CDC Fact Sheet on CFS If you're still feeling uncomfortable with your Dr's conclusion or final diagnosis, you might consider consulting an Infectious Disease Specialist. They are the best diagnosticians anywhere. Plus, if you DO have some infectious issue from Mexico or anywhere else, they can find it!
I worked for 10 or 15 years trying to figure out what was wrong with me -- seeing Dr after Dr, specialist after specialist. I just couldn't accept that I must have CFS, just because nothing else wrong could be found. In other words, I thought that Drs were "labelling me" with CFS because they couldn't figure out what was wrong with me. I mean, there are a lot of "syndromes" which can't be diagnosed, and I couldn't figure out what gave all these Drs the impression I had CFS and not one of those other undiagnosable illnesses and conditions. They were saying and doing nothing to convince me they had ruled out everything else. But the infectious disease specialist -- that's their job, that's what they do. So after a thorough workup by an infectious disease specialist, I finally felt as though I had been tested for everything known, within reason. So especially in your case I would suggest a consultation.
Guess that's all I can say for now. I would also agree with snohare, that hepatitis or other liver issue could be another potential cause for your symptoms. But it doesn't strike me as a strong possibility--not that I'm a professional or anything ;-)
Good luck sorting everything out. If you have any questions, please feel free to post them. And let us know how you're doing, if you want. Living with CFS, or any serious illness is a longtime, ongoing process, for which one might need support at any time--and that's exactly what the HealingWell forums are set up to do .