Doxycyline ans Azithromycin Treatment question

Hello (M)

The past 2 months have been painful. Had a constant stinging in urethra (not when urinating) urge to urinate, weak stream, dark urine and some discharge after urinating.

Ive been tested for Gon, Chlamydia, Syph, HIV and UTIs. All negative.

Beginning of last month I was treated with 7 day doxycyline. Symptoms went away a week after completing treatment.

Fast forward two weeks and I started having symptoms again. I went to the doc again and they said my results were negative and nothing appeared out of ordinary.

The doc gave me a single dose of zithromax (azithromycin) and said they suspected I could have mgen or ureaplasma. (Doc suspects it but they aren't able to test for it where I live)

Ive read you're supposed to take Doxy and Azi together. Does anyone know if It matters the time in between taking both meds for such instance?

Im worried because I was treated last month with doxy and now im only on the zithromax and If i needed to be doing doxy again after the zithromax.

Thank you.