Could it be something bad if i have scrotal swelling?

Yes: See urologist .This could represent varicocele, blood in area, trauma, or tumor. This should be evaluated immediately.

Yes if hard: Painless hard swellings of the testicle are cancer until proven otherwise. Hence should be checked out asap. Fortunately most scrotal swellings are benign. Scrotal swellings that develop suddenly and are associated with severe pain can be due to torsion (twisted spermatic cord) which needs to be corrected asap because testicle can be lost if left untreated>6hrs. Or epipidymitis which antibiotics a.