Most probably you could have strained the lower abdominal muscles which are connected to the testicles also known as cremaster. Sometimes you can pop a vessel due to excessive straining and a small blood lump can form there.
This cremaster muscle is responsible for the movement of the testicle up and down. when it contracts this pulls the testicle up and it comes down when they relax.
This muscle is now irritable due to the injury which might be the reason for excessive movements of the testicle.
Usually this should come down with rest and medications. If the lump fails to go, you should see your doctor who can order an ultrasound scan to confirm the diagnosis.
Avoid straining at all cost. Take a stool softener or laxative till this problem subsides.
Please let me know if you have any doubts.