Welcome to our forum Dcarroll797
I am sorry you had half your thyroid gland removed and I hope you get better quite soon.
I'm assuming the doctors presume that your thyroid gland will still function. Some people have reactions at first to levothyroxine.
If it is possible, can you get a print-out of your results of your last blood test from the surgery, they must include the ranges. Labs differ so it makes it easier to comment.
As you only had half your thyroid gland removed it might be producing thyroid hormones. Maybe that's why you felt ill. That's not uncommon to not feel so good when starting replacement hormones.
Some hints:- you should get a blood test every six weeks until you are on an optimum (which means you feel well with no symptoms) not when the doctor only goes by the TSH result and tells you you are 'normal' when you don't feel normal.
All tests should be at the very earliest possible, fasting (but you can drink water). Also allow a gap of 24 hours betweenlast dose of levo and the test and take afterwards. This may prevent the doctor adjusting dose unnecessarily.
Ask also for B12, Vit D,iron, ferritin and folate to be checked as we are usually deficient.
Levo is long-lasting and a dose you take today would take about 4 to 6 weeks to gradually leave your system.
You could try this test if you wish. Take one anti-histamine one hour before you take your dose of levo and if you don't have a reaction, you need to change your levo to another make.
If the present symptoms resolve after you take the anti-histamine refer to the pharmacist to get an alternative levothyroxine.
We don't expect to feel worse but many of us do until we got to an optimum dose or may have to try an alternative hormone but the NHS wont prescribe.