Between the constant vomiting and lack of sleep, my mouth was a mess! Yes, hormones and low immunity can trigger ulcers, just try to rest if your baby actually lets you sleep.
Hormones do cause ulcers sometimes, but staying hydrated and doing light morning walks really helped keep my digestion and body heat in check. Do ask your doc first before starting any routine though.
It can happen due to vitamin deficiencies or hormonal shifts, but please mention it to your gynac. They might need to check your blood levels or change your supplements.