I've been having this odd red rash on my legs that stings when it shows up. been coming and going for years along with red dots. can it be eczema?

Could be many things: Eczema, contact dermatitis, or even shingles, if you had chicken pox as a child. However, shingles would be rare in an adolescent with a normal immune system. Try switching to a hypoallergenic laundry detergent and bathe with hypoallergenic soaps. Patients with eczema have higher sensitivity to allergens. See a dermatologist if simple prevention does not help.