Do what you think is best. It really depends on how much pain you are experiencing. Glucosamine & chondroitin will help...and MSM will help also. Are you running in running shoes or cross trainers? Are the shoes new or old? Running shoes wear out about every 3 months, I believe.
Irregular exercise is bad for you. It hurts. I think that most people get used to running within 2-3 weeks. How often are you running? Every day, weekdays, every other day...? What surface do you run on? Asphalt, gravel, treadmill? If you're running on a treadmill at a gym, then try an elliptical machine. At what pace are you running (min per mile)?
Personally, when I have had aches and pains, etc from running, I continued through it. If it continues to get worse, then back off. If the pain is pretty bad, then I'd take a few days off. If you can, try to at least walk in place of running if you feel that you need to back off from running. That way you won't get out of your routine and you'll still be doing something to burn some calories.
15lbs in a month is good progress. Keep up the good work!