Ami-tex LA vs. Cran Tex LA?

hello. after sphenoid surgery, I was put on ami-tex la (twice a day)for headaches. it works beautifully. I might add I had tried several others to no avail. now I am told that the FDA has taken ami-tex la off the market and I will have to find something new. I tried cran-tex la, doctor prescribed once a day. I am told by doctor and pharmacist that they are the same thing. my question is a two parter. if they are identical then why hasnt the fda taken both off the market. when I researched the ingredients. I learned one was 300mg twice a day vs the cran-tex being 200mg. so wouldnt I need to take crantex la three times a day to equal the ingredients of amitex la? and if that is not enough questions, why can I buy amitex from one drug store but not another? I have been doing this now for at least 9 months. thanks in advance for any help you can give me with this issue.

sincerely,

Diana