Hi. Good to know you seem to be clear on your diagnosis of GERD. The discoloration seems to be some dilated veins near the tonsillar area. Maybe something called a telangiectasia. It may be inflammation due to an infection. Increased snoring maybe a sign of Obstructive sleep apnea(OSA). Tongue bites during sleep maybe again a sign of OSA or just macroglossia( a birth variant where the tongue is enlarged). Not to fear.
Next Steps
visit an ENT specialist. ask for an OSA evaluation. SLEEP STUDIES maybe required.
Health Tips
avoid consuming large meals. a short 20 mins walk after meals helps too. eat lots of fresh fruits and vegetables. Do not eat till your stomach is full. stop when you feel you require an additional small helping. try lying to one side rather then on your back. may prevent the tongue falling onto the back of the throat preventing tongue bites