Mine are usually eating hawthorn no problems, its me that gets bleeding fingers so I now only feed rarely.
I would have a careful exploration in her mouth, if she has a thorn stuck somewhere it should be painful and you will know about it....
Did you drench them or inject wormer? If drenching she may have got a bit of bruise where the gun went down, mine are very difficult to drench and it is usually a wrestling match, so metal bit could easily damage the back of her mouth a bit? Is she up and drinking, everything else ok?
Can you tempt her with some really tasty banana or other treat, that she would normally swallow easily, so you can see if there is something wrong with her mouth/throat or if it is something else?