Starting on a new pack (even if it was left in the car) wouldn't "stop" your period. It just starts you on a new cycle of hormones. It may be just that your period is going longer than normal (stress over things can do that). If it continues past 7-8 days then maybe talk to your doctor. If you feel the old pills have been comprimised by the heat, start the new refill. It's better safe than sorry. Did you take the first 3 active pills? If so, then I would start on the new pack today so you don't skip any days. I'm not sure if it matters to start where you left of in relation to the old pack or if you should take the whole first week of active on the new pack in addition to the 3 you already took (it probably would just delay your period next month).

Thank for your advice! I asked the clinic and they said to start off with the pill I was supposed to take today. I did take the first 3 pills in the last pack, then just switched to this one. I'm not really sure if the heat did get to them yet and not sure if my period has stooped but I hope to god it does soon. Thanks again!