I did great after Mepron and Zithromax...back to vigorous exercise for the first time in at least 15 years...But, it only lasted for 3 weeks. The everthing started comig back...paresthesias, lightheadedness, and excercise intolerance...nearly fainted at the gym (again). So, I am now on Biaxin and Mepron. I almost fainted again today at the gym, after only 20 min of moderated exercise. And, I have the worst paresthesias in my arms that I have ever had. I have been feeling nauseous and lightheaded often. Has anyone else ever experienced a Herheimer reaction like this? Or has anyone ever felt like this on these drugs? Thanks.