Thyroid (Variation in TSH) Advise.

Due to a pain and Discomfort in the anal region doctor advised to to do a Sigmoidoscopy, Abdoman Scan, Blood and Urine test. I gave the blood samples after doing Sigmoidoscopy on 1st March and in the blood test result my TSH came 8.51. Doctor gave me a 25 mg tablet also for Thyroid. But I did not start using it. As I never had Thyroid, I was doubtful and I did the TSH again on 4th March from a different lab and Now the TSH came as 4.2 Am now confused, do I have thyroid, should I use tablet. What could be the reason for it to shoot high on that particular day. Do I have to check this again from a 3rd lab. I the abdomen scan I have grade1 fatty liver, is this anyway related to this. please advise. Thank you in advance.