That's great that your partner was able to share this with you - they must care about your health as well as their own.  Many STIs are asymptomatic which means you can have one and not know it.  Even if you feel ok, the STI could be causing inflammation and problems for your body, and you could potentially give it to someone else without knowing it. Therefore its super important that you get tested. There are a bunch of different STIs, so if you can find out from your partner what they have, that will help your medical provider take the best care of you.