F/23 burning sensation in upper chest, radiating heat. worse when at rest. skin on chest very sensitive/irritated, no rash. has lasted on/off ~5days?

Anxiety vs....: Something! It is often hard to understand how feeling stress or anxious could cause skin symptoms such as these, but in a young person your age, that is the most likely cause. HOWEVER, the significant disease causes of this are in the connective tissue disease realm: lupus, scleroderma, dematomyositis, cryoglobulinemia, rheumatoid arthritis. Reduce stress, observe, see doc in 2 weeks if persists