Sore throat for 2 weeks, taking Carbimazole?!

HI guys, i suffer from hypertension (over active tyroid) i am currently taking 40mg of carbimazole as my thyroid levels are quite high, For the past 2 weeks i have had a sore throat......some days its worse than others and its stings whatever i eat...i dont have a cold..or a cough etc. When i had had the sore throat for 5 days i had emergency blood work done as a rare (i think rare) reaction to the medication is that it can lower white blood cells and symptoms are sore throat and mouth ulcers,,,the blood work came back fine so i carried on taking the medication thinking it will go soon...but it hasnt. I also got a bad mouth ulcer for a week...the week before i got the sore throat but havnt thought anything of it.
If it was lowering my white blood cell count would it have been picked up on the first blood work or do you think i will need another, i have never had a sore throat for more than 3-4 days :S...thankyou x