03 Spectra with 78k jolting

My daughters car started jolting about 3 weeks ago and she is just now telling me. She said when she was driving it would jolt and then yesterday it actually stalled at a stop. It started right back up. Today it worsened and then while driving home from school her engine light came on and stayed on. Any clues? Our shop cannot look at it until Friday. It rained yesterday and today and she said the jolting was actually worse. Not sure if this could worsen it or not? Any ideas on what it could be and what to check first?