please help me whats going on with my med...

I have taken one pill of bactrim ds, also known as sulfameth/Trimethoprim 800/160. I too about lunch today for a spider bite i got the night before my leap surgical procedure so during that the dr said he thought i had gotten THAT COMMUNITY STAFF like MRSA that 99.9 percent people have but not my body is itching all over, i have chills, and my back is burning, I feel different all around kinda like im in another world and very sleepy but cant sleep. Im not really having many emotions or feelings either,I just feel like I dont care and that is taking 1 pill at noon and 1 around 10pm. I dont no what to do I have 2 babies under 2yrs of age and I need to get better but i dont no if the med is safe. And I am getting bruises for no reason.