Toddler running a fever with pinkish/reddish gums. cries when chewing food.

Teething: This sounds very much like teething. It is normal to get low grade fevers when a child is teething. For more information, see below http://www.health.govt.nz/your-health/pregnancy-and-kids/first-year/6-weeks-6-months/teeth-and-teething

Sore gums: Probably teething. If under age 1, check in w Pediatrician. If overage 1, check in w Pedodontist. Try gently rubbing the gums, cold teething ring, liquid analgesic if Dr says it's OK.