Rash on Penis

So over the past 3 weeks i have had this rash that comes and goes, there is no pain only slight irritation. I took a herpes test which came back negative so i can rule that out. There is no burning when urinating or anything like that. 

Any help would be fantastic!

Possibly a fungal infection? Might be worth trying an anti-fungal cream available at any pharmacy eg Daktarin or Canesten. 

That just looks like mild balanitis.  These links may help:

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

https://patient.info/doctor/balanitis-pro  (written for doctors)

Washing (with water, no soap) daily, and taking a leak and washing after masturbation or sex will probably help, and you could also try Canesten cream.