Baytril and Fortaz are both antibiotics, you will need a vet visit to get them. Also one of my vets doesn't stock Fortaz, apparently it's expensive and has a short shelf life, so she prescribes Baytril + Naxcel in combo.
Your warm side belly heat should be closer to 90*F and yes, you definitely need a t-stat for that heat pad, most run well over 100*F if unregulated.