Red spots on penis

Hi there, so basically I met this girl and we've been going out for about a month. 2 weeks ago we had sex for the first time and now I developed some red spots on my penis, they go away completely but reappear after masturbating could anyone tell me what's wrong ? I'm really worried

It's probably just balanitis, but a pic would help.  This should help you add images:

https://patient.uservoice.com/knowledgebase/articles/402861-how-do-i-add-an-image-to-my-post

If you're using a phone or tablet, you may need to choose the desktop/PC option in your browser.

If it is balanitis, these links may help, though the second one is written for doctors:

https://patient.info/health/balanitis-leaflet

https://patient.info/doctor/balanitis-pro

Take a leak and wash down there (just water, no soap or shower gel) after having sex or masturbating.

Here how it looks at it's worst day after masturbation and its gone completely again few hours later 

I'm not a doctor, but that looks like balanitis (male thrush), which isn't normally a big problem.  Peeing and washing after sex or masturbation should help.  You could also try Canesten cream (which is usually for athlete's foot or thrush in women, but also works for balanitis.

Okay thanks for the answer I just hope it isn't herpes if it would be I think it wouldn't just disappear ?!

Correct.  It doesn't look anything like herpes anyway.