After I have intercourse, my penis feels swollen and small red dots appear on the glans. It can be itchy and uncomfortabke. Blood/urine test clear std?

Yes, get tested. You should absolutely visit your doctor. Your doctor should do a physical exam. Make sure you ask to be tested for stds. If you have had multiple partners, high-risk partners, high-risk intercourse, or unprotected intercourse, you should consider being tested for HIV as well.
Infection. Sound like it might be a candidal or yeast infection. This usually is more common in uncircumcised males but you should talk to your doctor.