Hi and thanks for your question
Yes, it is possible to have pain with no discharge with an STI. In fact, most STIs can have a variety of symptoms ranging from every classic symptom, some possible symptoms, and commonly no symptoms at all.
If you are sexually active, we recommend visiting a clinic to be tested for sexually transmitted infections including HIV, syphilis, gonorrhea and chlamydia.
Have a look at our Clinic Finder to locate a clinic in your area
You might also like our STIs at a Glance chart which gives an overview of many STIs and the possible symptoms associated with them.
Let us know if this does not answer your question or if you have any more questions or concerns.