Paroxetine Hydrochloride and sided chest pain

Left-sided chest pain from about one week onwards of taking 20mg of this drug; been on it for less than a month. Had lots of heart and lung tests in A & E to no affect, ie, they cannot find anything. It is intermittent, about 3-4 times daily, from one quick stabbing pain to about 10 mins; it gradually dies down. Taking deep breaths is not advisable due to the pain, but I just take more shallow breaths. These episodes do not bring with them any other side-effects, although of course I usually stop what I am doing. Nothing particular brings them on, I can be just lying in bed with eyes closed and have just woken up. I have been on this drug last year without chest pain. Not taking it for depression; taking it for although health worries, with my left thigh feeling 'strange', therefore, I think I have every muscle wasting disease under the sun. No therapeutic affect as yet. Is the chest pain due to the drug or something else? I could only find chest pain as a side-effect on the *****website; not in the British doctors formulary (BNF) at all. What's going on? I am close to asking to change to Cipralex, similar to Paroxetine.