Implant messing with my cycle

Hi everyone,

After having an estrogen implant, my cycle has been so off. Usually a few days after intercourse I will have some irregular spotting of old blood then a few days after it will be a full blown period. Condoms are used in the intercourse. I will eventually go to a clinic and test for STI but I have no symptoms at all other than the spotting.

I’m just so worried and I don’t really know what else to do. If someone can reassure me or anything that would be amazing. Love y’all