Thanks for your query,based on the facts that you have posted it appears that you have Epididymitis
and have been taking antibiotics antibiotic.off and on .
Epididymitis in your case may be secondary to STD that you had .
Please consult qualified Urologist
for clinical examination and get following basic tests done to confirm the diagnosis.
1)Routine Urine test and Urine culture to find out the organisms causing this infection and antibiotics to which they are sensitive to.
scanning of the scrotum
There is no term like strong antibiotic to combat any infection it is appropriate antibiotic detected on culture that helps to control infection.
Please take broad spectrum antibiotics like Cefexine along with urinary antiseptic like Nitrofurantoin
twice daily and urine alkaliser thrice daily.Later on switch on to appropriate antibiotics as per culture report.
Please note that Epididymitis takes long time to get cured hence you will need to take antibiotics continuously for 3-4 weeks.