Congrats on the weight loss!
I'm no expert but if you start to hurt during your routine, you should stop and stretch or just walk. If the pain does not go away after stopping and or stretching, definitively stop what you're doing and start R.I.C.E.
Rest,Ice,Compression, Elevation and take some NSAIDs.
I've tried to run through sharp pain and dull achy pain only to find that I've made my injury worse. I pulled a calf muscle once and thought it was just a cramp and ended up being side lined for 3-4 weeks-not fun.
However, the day after exercising, you should feel a little sore & "tight", but your mileage may vary depending on how hard and long you exercise.
2013 Race Schedule
2/3 Sac State Superbowl 10k 55:20
4/7 Sactown 10miler 1:47
4/21 Capital City Classic 10miler 1:42
5/4 American River 1/2 2:37