I Use A Steriod Inhaler,and Developed Thrush Mouth, Dr. Gave

I use a steriod inhaler,and developed thrush mouth, dr. gave me a antibiotic, I do believe ever since I compleded that me for thrush I have nausea that come in waves, and I do have gastric ulcers, could the antibotics damaged the lining in my stomach?, and what can I take