I Have Been On Eltroxin 50 Mg. For 12 Day's

I have been on Eltroxin 50 mg. for 12 day's I have a very dry mouth at night that wakes me up every 1- 2 hours I need a drink desperately . This goes on all night during the day I have not noticed it. This morning I noticed a lump under my left side gland , on my neck. I had my left side thyroid removed on April 27, 2015. I could not tolerate synth rood 50 mg pills . Could this now be a side effect from the Eltroxin medicin?