battery overheats and drains quickly when not connected to power

Hi everyone.

Recently, my battery has had a "Service Recommended" symbol pop up and I've also noticed that it drains quickly + overheats when I'm using it. I contacted Apple Support earlier and chatted with a few representatives. They told me to check my cycle count in the "System Report" area and this is what was there:

 Charge Information:

 Fully Charged: Yes

 Charging: No

 Full Charge Capacity (mAh): 5318

 State of Charge (%): 100

 Health Information:

 Cycle Count: 494

 Condition: Service Recommended

But I was told the cycle count and charge capacity were probably not the problem. I tried resetting the SMC after that was suggested but nothing changed. I made a Genius Bar appointment but since I'm a student, I kind of need my laptop every day for pretty much everything so any help would be appreciated.

Thank you!