Should we go to the ER?

Okay you know how sign of infections is red streaks in the skin?

I don't know what the shit is happening to my so. But he has severe pain in his arm.

The pain is in the armpit and shooting down the arm.

There is no bump or mark or any swelling in his arm pit but tonight there is a fever and a red streak going down his arm.

I'm forcing him to see a doctor. But I'm not sure if this is absolutely an emergency and how fast we should act. I'm convinced that it's an infection and he needs antibiotics.

I'll post a picture soon. Probably going to shave his hairy armpit to see if I can find a bite or something.