Welcome to our community! I'm glad you found us.
I had muscle fasciculations so severe while infected the first time that I would literally "bounce" off of anything I was sitting or laying on at the time. It scared both me and the doctors that saw it. Yet, treatment for Lyme and co-infections cleared it completely, and even though I got reinfected I still have not had that happen again.
It's rare for just 4 weeks of Doxy to clear a Lyme infection, so I would say that it's most likely you never healed to begin with since these symptoms have continued, and you have a confirmed Lyme infection. Without effective treatments, the infection just goes into hiding.
I would greatly encourage you to skip the GP and find a Lyme Literate M.D. and get started with appropriate treatments. If you need help in finding one, we can likely be of help.
If you haven't yet, it would be helpful for you to start with reading through the thread at the top of the forum titled,"New to Lyme?...Start here!!", as it is packed full of important information, symptom lists, helpful links and pdf's, how to detox when one has these infections, information on probiotics and much more. And this is another good list of possible detoxing routines: www.tiredoflyme.com/detox-methods.html