Every now and then I will get these hard sore lumps under my skin on my chin and they have swelled and very sore. Could it be something im eating?

Cystic Acne. Cystic acne is a severe type of acne characterized by large, swollen lumps that appear under the skin. These cysts are usually filled with pus or fluid, but can also consist of a hard, swollen mass. Cystic acne usually lasts longer than regular acne. Treatment is with oral antibiotics like solodyn (minocycline) or monodox.