I Believe A Spider Bit Me-8" Red Line From Bite. Is It Infected Or Could It Be Poisonous?

To have any idea if you may have a poisonous bite or sting you need to be sure what it was that may have bitten you. You say you think you may have been bitten. You need to be sure about the circumstances regarding this. If you saw a spider bite you then you need to determine what kind of spider it was. This can depend upon your geographical position. There are many different types of spider around the world, many of which are not poisonous to humans, though there are several types which are extremely dangerous. Your description is incredibly vague and from this it is not possible to work out if you have been bitten and, if you have, what by.
The best advice is to seek immediate medical attention in your local area. A local doctor would be able to advise you as to whether a bite or sting is infected, though they may need some information and a description of what it was. You describe a red line forming, this could mean it is just a simple matter of a flesh wound or a reaction to a venom carried by the creature.
All this is extremely hit and miss and with such matters there is always a risk and time is of the essence, so it is best to see a doctor as soon as possible.

The red line is a bad sing you need to get to a doctor if it goes to your neck or heart it can KILL you

It sounds like cellulitis. (not sure of spelling).  My 10 your old son had a small sore on  his arm and the next day had a red streak going from it.    I  took him to ear and the doctor said that was what it  was, never did figure out what, if anything, bit him.. Hope this helps.

I got bit I'm guessing from a spider.. But I have to dot where it bit me and a red line running towards my chest..

The bite is in my bicep.. And the line is like  2 1/2 inches long

I was also bit just above the elbow inside of my left arm.   I woke yesterday morning and the bite had a red line running up from it halfway up my bicep.   I now woke up today and the line is smaller and going back down to the bite.   I marked it with a pen last night to see if the line would move or enlarge.   I don't know if this was smart or not but last night I popped the head of the bite and sucked on the bite spitting out the clear liquid, then poured hydrogen peroxide on the head and put neosporin and a band aid on it.   Like I said its better today....I just cleaned it again when I woke up...In all honesty though I may have got extremely lucky you should contact a nurses line or something and ask advice.

I have just been bit also the line you speak of is the major sign I have found for a black widow bite. You have the line go to the er.