Too anyone on 50mg of sertraline find that they have these side affects...

Headaches often
Muscle pain

I've been on these tabs nearly 4 days now as Before I was on 25mg for nearly 5months but noticed they wasn't working so Iv now been given 50mg but I'm gettin horrible side affects.. Just wondering how long this will last? Answers would be great to anyone else who is also on these tabs thanks