Left posterior side tongue red, swollen in distinct pattern, no ulcers, painful to swallow. Cant eat. -7lbs in 3 days Should I see a doctor? What kind?

PCP or ENT. I would start with your primary care doctor and have him/her examine you . This could be infection or inflammation in your mouth/tongue and could be treated with anti-inflammatory meds and perhaps antibiotics. If this is more serious your PCP will direct you to ENT.
Yes. You need to see a doctor and get some treatment. An internist will be of help.