Well, the relationship between the intake of
synthroid and alcohol intolerance is not very well documented, but it is worth noting that excessive alcohol intake can cause flushing, palpitation while synthroid itself may also produce side effects similar to alcohol, so it is possible that these two substances produce an additive effect in causing the problem u have mentioned before.
I suggest you check with your GP to make sure that the dose of synthroid is not too high for you now as the problem may be a sign of overdose.
Hope this may help.