I am very overweight I know I'm around 5 ft 7 I'm 20 year old female and I weight roughly 22st

I noticed this evening a lump under my skin about 2.5 cm long only about 1 cm wide it's in the crease under my stomach overhang it's quite hard and is sore if I touch it Also it is purple ish in colour on the surface

I also have a reoccurring yeast infection in the skin fold as well if that means anything

Does it need treatment should I be as concerned as I am