Unfortunately, 4 weeks of antibiotics is almost never enough to even put Lyme in remission. I wouldn't call what you are experience a relapse so much as a continuation of your original illness.
If you can, you really should see a LLMD (lyme-literate MD). They specialise in treating Lyme, and will give you the treatment you need to get better. There is a member here who has a list of LLMD's and can help you out (I think it's Ticker, but I could be wrong...someone will be along to correct me and give their email address soon enough I'm sure). I don't have the information right now, I'm sorry.
But the important information to have is that Lyme disease requires more than 4 weeks of antibiotics, unless you are very, very lucky, and catch it very early.
If you want more information on treating Lyme disease you could go to the ILADS (International Lyme and Associated Diseases Society) website. If you click on the link for "Dr. Burrascano's treatment guidelines", you will get a pdf that describes in detail the general treatment plan followed by LLMD's. (Your Dr may not follow Dr. B's guidelines exactly, but you can use them as a reference to see approximately what sort of treatment is required, and for how long).
I'm sorry you're feeling worse. Hopefully there is no damage to your eyes!