My doctor would have had me put in restraints if I had gone to the gym after only 6 weeks out from DaVinci - he wouldn't clear me for anything other than walking until almost 12 weeks.
For the infections - one issue I had was incontinence - having to use 7-8 pads a day for months. At first I was not changing them often enough. The dampness seemed to have been provoking back-to-back Urinary Tract Infections. I have three that required heavy antibiotics and kept coming back, one more that was lighter and cleared up with an older $4 generic.
One thing to check with the pharmacist or doctor - are you eating / taking something else that might limit the effectiveness of the antibiotic? They tell me not to use dairy products or take antacids for several hours before/after the meds.