Chlamydia in a relationship. Help

I’ve been in a faithful relationship with a girl for over a month now. I also had a different sexual partner about 3 weeks prior to this.

Anyway, I had a bit of irritation/itchiness on my penis tip a few days ago + burning sensation when peeing so I got tested and it was positive for chlamydia. 

Firstly, could I have contracted it from the other girl nearly 8 weeks ago and the symptoms only show up for me now? I have asked her and she said she has no symptoms but will get checked tomorrow. 

I do not want to falsely accuse my girlfriend of cheating on me + giving me the sti.

Any advice?

Thanks for your responses. 

I think regardless you are going to have to sit your new partner down and tell her as she too could be infected.  It can take time to show signs so could be from either but both of them need to be tested to ensure whether they have it or not.

<sarasm> Wow a faithful relationship for a whole month<sarcasm> Does anyone practice safe sex anymore? Maybe your GF had chlamydia from a previous relationship. 

Then he said he had a sexual partner 3 weeks ago. Something doesn't sound right.

Nevermind i read it wrong