I went to the doctor and found out i had a uti well when i got home my left ball was swollen and became painful i later ejaculated blood why?

Epidydimitis?: UTI is not common in males. Usually underlying etiology has to be worked up. I suggest going back to your MD for further work up esp testicular US needs to be done ASAP

Immediate treatment: You have orchitis or epididymo-orchitis, usually a bacterial infection of the testicle or both testicle and epididymis - this requires IMMEDIATE evaluation and strong antibiotic therapy