looks like jock itch
This is most likely an infestation of some kind: usually a yeast / fungal infection, you may also have a insect infestation.
Get help from a pharmacist / chemist on how to treat this - look up dealing with jock itch.
Do not shave the area until it has cleared. Try not to scratch the area as this will make things worse.
If you are doing physical training of any kind, such as for the football, or do workouts you must put on freshly laundered shorts for every session - even if you do 2, 3 or more brief sessions a day.
When you shower try not to apply soap or whatever body wash you use directly to the area, and do not use hot water - make sure to carefully and fully dry the area so no moisture remains.
Do not share a towel and try to use a freshly laundered towel everyday if you can.