Ultrasound for both testicles or one testicle?

[netterman]

Hello,

I feel a harder area lump and discomfort at my right testicle bottom area.

I told a doctor about it and he wrote a form to request an ultrasound to the right testicle.

My left testicle felt normal, but I am not too sure if it is really normal, should I get the left testicle ultrasound too?

Can the doctor feel if a testicle is normal just by touching/feeling the testicle?

Do you guys do regular ultrasound for testicles yearly even if they feel normal? I read that men should check for testicles lump, but I am not too sure check myself how as I read some "tubes" might be mistake as lumps.

I read sometimes erection or ejaculation happens during ultrasound, is there any ways to prevent it?

Thanks a lot.