when it is like 100 degrees F outside (just about body temp) you feel hot instead of feeling perfect since its the same temperature outside as in your body?

Various reactions in your body produce heat. You may produce more heat than you need. If the air is at the same temperature as your body then it makes it harder for you to shed the excess heat.

The skin temperature is slightly cooler than the body core temperature. This allows heat transfer. What is interesting is that if one goes into a hot tube set about 95F one will initially feel warm but will get cooler within time. The same air temperature will make one feel hot all the time. It comes down to heat transfer being better in water than air.