the thyroid is not under your chin. it is in your neck. unfortunately since i can't see those lumps. feel those lumps. i cannot blindly determine their nature based solely on your vague description. if those lumps are shallow and moveable under your skin and you feel they are related to your acne they could be acne cysts. you would need to see your medical provider or a dermatologist to be sure.
i have two small lumps under my chin that vary in size. one is on the left side and the other on right side. i am 20 years old. im uncertain if it is a pimple that never broke through my skin or can this mean that i may have a thyroid nodule(s)?