If I used (4 months) and stopped taking oral tetracycline for half a year and start again, will it be ineffective (possibly from bacteria tolerance) or will it still work?

Background:

I took tetracycline medication pills twice a day consistently for four months and I never saw amazing results. This was well over half a year ago and I never refilled my prescription and just used my night time "Bianca - clindmycin phosphate and tretinoin" which didnt help and now my skin is crazy acne prone. I am currently waiting to go to the dermatologist but until my appointment comes, I have been on tetracycline again.

I've been taking it for a month now and my skin has just gotten worse will breaking out constantly with cystic acne