What can I do to treat, what I believe I'm experiencing, thrush or thrash? I've been taking an antibiotic for 4 days and my mouth is always "dry", I have little sores on both sides of my lips, like herpes simplex (cold sores), and it's become very painful to brush my teeth. It was suggested that I rinse my mouth with warm salt water, & I have twice since trying to brush teeth! What us a remedy for this "side affect" of taking the antibiotic cephalexin or kelfex?