Sertraline is a very common antidepressant. Side effects tend to wear off after a week or 2 and it can take 4-6 weeks for them to reach therapeutic dose and for you to feel any benefit, the same for any dosage increase. If you can't cope with the side effects then please go back to your GP. And if this one doesn't work for you, please don't give up. Sometimes it takes trying a few different ones to find one that works for you. It's very trial and error I'm afraid.