I just took a glance at some of the most common side effects listed in our Drug treatments booklet. I didn't see this listed but that does not mean it's not related.
Do give a ring to our helpline and ask to speak to one of the nurses. The helpline is open until 8 this evening and 2pm on Saturday.
That said, this sounds really awful. It might be worth calling your GP surgery ASAP.
I hope this helps.