Need quick advice regarding Hyperthyroid meds!

I have a 13 year or older cat Girlie (age is a guess since she was an adult feral when found).

She has had weight loss over the past year or so, very drastic recently.

In the past month she has dropped to under 6lbs and now at 4.9lbs last weigh in.

She has been eating and drinking throughout the day.

She has had kidney and urinary infections and those have been treated with antibiotics.

Last year her thyroid levels were normal and now borderline.

I do not trust this vet I took her to and to make it a short story will not be going back.

I have only taken her there a few times since about 11months ago.

I need to find another vet and get her properly tested but in the last visit, which was a few days ago,

I left with an Rx for Methimazole to treat "as if" in an effort to stop the weight loss.

My concern is this...I got the Rx filled today and started her on it. 

Tonight I was online researching this medication and every website says the dose should be started low and gradually increased.

He gave me what I think is the strongest 5mg/mL and now I am worried this will do more harm than good.

I could use advise from anyone experienced if I should continue or stop the meds.

It will be a day or two probably til I can find a new vet since I need to make some calls tomorrow and make an appointment.

She has been losing about half an oz per day which does not sound like a lot but given her current weight and skeletal condition is.

I am scared to give it again and scared not to and really at a loss...

Also if anyone has a referral for a good vet with these conditions (kidney/thyroid) in the Orlando area or north (as far as Daytona) it would be very helpful.

The Dr should have started you off on the lowest dose and after a couple weeks is supposed to retest her to see if he needs to increase the dosage or not. My cat has both kidney disease and hyperthyroidism and she gets 1/4 of a pill, twice a day which is the lowest dosage and she does well on it. She stopped eating for a couple weeks when she was diagnosed with kidney disease about a month ago but I started her on Kidney Gold Support drops and she got her appetite back within the first day of starting so maybe you could try that?  In the meantime I'd get another vet and get your cat rechecked. And feed your cat anything she will eat so at least she has something in her system and hopefully won't continue to down spiral in weight.

Thanks, I am finding a new vet first thing tomorrow and hopefully can get this sorted.

Appetite is not an issue with her. She eats and drinks all day and night, has wet and dry food available 24/7.

I have been feeding what I think is good quality food (grain free chicken canned and dry Blue Buffalo).

I need to look into best diet for this type of condition and if I need changes will do so.

I wouldn't cut the dosage until I got some advice from another vet. Good luck.

Have her checked for diabetes as well since that, hyperthyroidism, and kidney disease can all cause weight loss even if she's eating and drinking a lot.