I Have Done Some Dental Work In Past 2 Month.

I have done some dental work in past 2 month. in last week visit doctor give me shot right in to my nerve so its was very painful. now its numb for a week. and every time I touch my teeth on that side my tongue get more numb and feels like some medicine licking out tooth to create that feeling. some what going in to my throat and create dryness and scratching sensation . I did go to my dentist. they looked at me like I am crazy and there is nothing can leak from teeth, they told me I have to go and do screening for mri. its to expansive I cant afford it... are they just try to make money... my teeth been done before in different country's some of them using tiny cotton balls to numb nerves...so i thought its common thing...I dont know i am lost...