Not even an MD!
But..for starters...have you had a PSA check?
As for Tamsulosin-it is a good drug for BPH-but its efficaceousness(?) will deteriorate in time. The side effects you describe do not seem quite right unless you already have the low blood pressure. Just check the dosage..normal I think is 400 micrograms a day but I do not KNOW that!
Very much a case for the second opinion I would have been thinking.