Both yawning and swallowing difficulties can be seen with MS, but I suspect your
yawning, at least, was from the Lexapro. I had severe
yawning with Zoloft, so much that I had to come off of it.
I also have swallowing difficulties. Sometimes it feels like suddenly I have forgotten how to swallow. Once I get it started it usually is okay. It can be a symptom of anxiety, but for me it isn't. Anxiety is definitely not one of my problems.
Stay a while and tell us about yourself.