Can a large pimple on my chin cause swelling under the chin? i have a soft tender lump under my chin, have had them before- thyroglossal duct cyst?

Lump under chin: First, unless you have been diagnosed with one previously, a thyroglossal duct cyst is rare and something that has likely been searched out on the internet. Second a pimple, carbuncle, or furuncle can cause tender lumps under the chin which may be either a swollen lymph node or an actual cellulitis or abscess of the anterior neck space. See your doctor.