Whats wrong with my dog?

i recently took my dog (american staff) to her first vet visit after adopting her from a shelter. she had kennel cough and worms other wise healthy and happy. after giving her doxycycline(for the kennel couch) and drontal (for deworming) she is very lethargic. she isnt vomiting, has loose stool with no diarhia, she coughs up phlegms, will not eat her food but seems more then ready to eat human food. doesnt want to drink water. her abdomin/ bottom half of her body shakes like if she want to vomit breathing a little faster but not significantly. i took her for a walk and she walked but not at her usual high speed. like i said she pooped but it was a little loose. she peed twice. after the walk she was even more lethargic so im guessing it took her whole strength to go out. she doesnt come to me when i call her. she is house broken and no incidents have happend inside the house. is this because of the mdecations and i should give her a couple of days or is it bad?