Of course always rest an injury and get it checked out but thankfully I have only had aches and pains that have responded to rest days. I only had a week off once with a shin pain and carefully got back into running. However, after graduation, I got up to a 10k each week when a tightness in my calves made me stop all long runs and I thought I might be finished. Just to encourage you, I dropped down to 5k walk-runs for several weeks which was amazing to keep me running and build my fitness again. No idea what caused the problem but slowly, it improved and has now completely disappeared.
This week I ran a 5k, an 8 and a 10k which was very comfortable and done at a 7.30 mins per km pace - so don't give up, find a kinder way to run and keep going out regularly