What's the problem with Tamsulosin? If it's giving you low blood pressure problems take it in the evenings, not the mornings.
It can take a long time to take effect: close to a year with me, and then only really after I started on Beneldopa for other problems, though the specialists think a link is unlikely
Are you taking any other drugs e.g. beta-blockers like Propranolol, or any ED drugs? Together they can cause havoc with blood pressure