Recurring balanoposthitis

About me:
-25 years old
-no allergy history
-uncircumsized
-intimate hygiene: regular, wash w water (no soap) & dry ok
-one sexual partner
-don't use condoms, lube

The problem has been recurring for the last few years (1-3 times/year).
Symptoms:
-small red dots on the penis head and under the foreskin
-no itchiness, no problems with urinating or anything
-if not cured, the amount of spots would increase and there would be certain discomfort during the intercourse
-girlfriend has no symptoms

Every time I applied clotrimazol 2-3 times a day for 7-14 days, and it helped.

I'm currently having the symptoms, and the previous episode was half a year ago. At that time I checked for Chlamydia trachomatis (PCR), Neisseria gonorrhoeae (PCR), Trichomonas vaginalis

(PCR) and it all came back negative. Monitored sugar in urine for 2 days - none.

At the same time my girlfriend checked for:
-Chlamydia trachomatis (PCR) negative
-Mycoplasma genitalium (PCR) negative
-Ureaplasma urealyticum (PCR) negative
-Trichomonas vaginalis (swab) negative
-Neisseria gonorrhoeae (swab) negative
-Candida (bacterial inoculation) no growth
-Gram positive coccobacilli (Gram's stain) many
-Ureaplasma parvum (PCR) positive (concentration over 10^4)
-Gardnerella vaginalis (PCR) positive (concentration over 10^4)

Then I checked for Gardnerella - negative. She started the Gardnerella treatment (Ornidazolum pills + suppository, no sex during). After that treatment we didn't have any problems until

now. However, several months after that treatment her analysis showed Gardnerella again. Although she doesn't and didn't have typical symptoms (no smell, etc.).

She also previously checked for AIDS, syphilis, hep C - neg.

Obviously, finding the cause of balanoposthitis is the priority.
-what else could've caused it? what tests would you recommend us doing?
-could it be streptococcal bacteria? how to check for it?
-could it be gardnerella? why did it return after the treatment? should she treat it againg?
-could it be ureaplasma?
-is it a good idea for me to use clotrimazol? should my girlfriend also take medication when I have the symptoms?

Thank you.