You absolutely, unequivically need to go to a doctor!!!!!!!!!!  Why are you worried about what could happen when you should have had the appropriate tests run already. 

As to your potential work comp claim, the real question becomes what are your damages?  If you have insurance, then maybe the cost of co-pays?  If this spider bite turns into a serious medical issue then you may want to consider your options.  If it is only a bad bite, you probably do not want to put yourself at risk.  Most states are at-will employment states which means you can be fired at anytime for no reason at all.