This is very common in Doha now a days,causes yet to know.But frankly speaking you did not mention here how much the value you have at present by the blood test revealed.As I do practice here first re-place the insuficiency by injections why ? ofcourse the potiency of the drug will rapidly get to the noraml target i.e. 30-8o. Your doctor will investigate why you have this deficiency could be any reason for that. Exposer to Sun will just normally help every one but sudden low should be properly investigate.Till then cheers !!