Cholesterol testing-how accurate?

I am a bit bummed right now. I had my 6 mo blood tests done back in November and my cholesterol had dropped from 288 to 181. That is a 107 point drop and I was thrilled! Well today, they had this lady at WalMart who was doing free screening for cholesterol for some drug company which apparently wants to get it's foot in the market. I thought "Ok, let's see how much lower mine has gotten since Nov.". Now remember I had the 6 month blood panel done at a hospital and blood was drawn from my arm. This lady *****ed my finger like you would do for a diabetic test. She could not get much blood to come out because, according to her, my hands are too cold (I posted about this earlier). With the blood she was able to squeeze (literally) out, she put it in this little monitor and came up with a cholesterol reading of 210. That is 29 points higher than what the hospital had me in November--and I have been losing weight-not gaining. Can anybody tell me how accurate or inaccurate these tiny monitors are? I have not changed my basic eating and there would be no reason for the cholesterol to go up. Medical people? Nurses? Help!! Tootsie ( feeling low)