Welcome to HEALTHCARE MAGIC..
I have gone through your query and can understand your concerns...
As per your complainred bumps at the back of the tongue and metallic taste
in mouth can be due to aside effect of the medicines given to you post extraction..
The bumps at the back of tongue can be due to inflamed Circumvallete Papillae which contains taste buds
and these Papillae are normally also slightly raised, so better consult an Oral Physician and get evaluated..
The bad taste can be due to side effect of medicine while other causes can be infection in the region of extraction socket..
The white spot can be due to injury
to the mucosa by extraction instrument and it will heal gradually on its own..
Nothing to worry consult an Oral Physician and get evaluated and get treated accordingly..
As of now use a menthol or mint flavored mouthwash to gargle ..
Drink plenty of water..
Hope this information helps..