I'm afraid it is likely your partner had other partners, for two main reasons. First, chlamydia rarely persists 2 years. It can happen, but usually the immune system generally clears it within a few months to a year. Second, when chlamydia causes PID (tube infection), it usually does it soon after it is caught, not months or years later.
There are exceptions and it is possible you've been infected a long time, so this is isn't proof he cheated. But it's the most likely explanation for all this.
U said before... as in before you two ever had sex or before wen yall had had sex but came back neg? Basically if u tested before yall EVER had sex then he would have already had chymidia then giv to u .. but if wen u tested negative WAS AFTER yall had already had unprotected sex..then that means u were clean then and if showed up in april then he cheated.. if too confusing then basically answer first question..
Well if you tested negative before while with him then the infection came from him. Could he have had it from before you were together yes. Could he have cheated...yes. No real way to say.