My right leg feels like its on firer

See a Dr!: I cannot tell what is causing your symptoms, but you should have it seen by a Dr as soon as possible! Possibilities include cellulitis (infection), thrombophlebitis (blood clot) or even sciatica (a pinched nerve). There are other possibilities, but the first two I mentioned are the most serious and need to be ruled out, especially if there is swelling and redness where it hurts!

Leg on fire: May be B12 deficiency, especially if you have an intestinal disorder like Crohns, neuropathy from diabetes, HTN , alcohol ,electrolyte disturbance like magnesium, or nerve issue from sciatica, meralgia parasthetica( espeically if overweight), autoimmune disorder , lyme disease ,early shingles before the vesicles appear, hypothyroidism. Rarer cause can be MS, F/U with doctor/urgent acre.