@jamiejames
Your taper may be too much. The best advice on this site is to taper off slowly and to take as long as necessary to do it. Dropping 37.5 may be too big a drop too fast for you. Please read all the posts on this site for more information.

During my research, a writer pointed out that the doctors prescribing this stuff and helping you get off very rarely have ever taken the drug, or experienced withdrawal themselves and another writer (I think that one was a doctor) said in these situations (what you are feeling), the patient is rarely wrong.

"For some people, discontinuation symptoms can feel as if their depression or anxiety is coming back, and indeed, stopping your antidepressant may increase your risk of relapse. Because of this, it's important to distinguish between discontinuation syndrome and relapse. The biggest difference between the two is that discontinuation symptoms typically begin within a few days after stopping your antidepressant whereas a relapse normally takes longer to occur and the symptoms develop more gradually.

Another difference is that discontinuation syndrome often involves physical symptoms that aren't associated with depression or anxiety, such as dizziness, nausea, or flu-like symptoms. With discontinuation syndrome, the symptoms eventually go away, usually within one to three weeks, but if you're having a relapse of your depression or anxiety, the symptoms don't go away and may even get worse. Additionally, if you start an antidepressant again, discontinuation symptoms will resolve quickly, but depression or anxiety will take longer to respond."--https://www.verywellmind.com/tips-to-reduce-antidepressant-withdrawal-symptoms-1066835

I took Effexor for hot flashes because I could not take hormones to control them. I never had anxiety issues. Six weeks after slowly tapering off 25 mg, I began experiencing anxiety, fear, akasthisia, etc.,--all discontinuation effects. Effexor affects your brain and how your neurotransmitters work; it will take time for your brain and neurotransmitters to balance. Go as slow as you need to.