Hang in there and just stay calm Andrey. You are just one month post vasectomy. You probably have a hematoma pressing on some nerves. Time is your friend. I suggest warm baths and ice. Alternate. The doctor will give you anti-biotics and anti-inflammatories. I think if you have an infection, which you may not, a course of antibiotics may help but really often times it has nothing to do with that.
You will probably be okay.
I got a bad case of epididymitis at year 3 after my vasectomy. The back of my testicle blew up to about 5 times it’s normal size. I took Bactrim and Etodolac and it resolved. I ended up getting a reversal at my 5 year anniversary. I have no testicular pain at all anymore. I’m here because I have nerve dysfucntion/damage high up in my groin on the left side that gets aggravated when I sit too much. I would not do anything for at least 6 months. I suspect in the next month or so you will start feeling much better with treatment.
Take it easy man! You will be okay.