If your vagina is really tense, the speculum might be painful. Also, it can catch on the skin sometimes and pinch. Ask your doctor to use the smallest possible speculum during an exam, and be sure he or she uses lubricant on it.
The back of the vagina has no nerves, so there should not be a searing sharp pain at the end of the vagina where the uterus is, even if he used something pointy (which he will not have done).
If you don't trust your doctor, go to a different ob/gyn and have an exam and explain that you are afraid the first doctor damaged you.
Regarding the air bubbles, if you recently had this exam, it is normal for some air to get into your vagina, and what goes in, sooner or later must come out.