Can I use a tampon while I'm "spotting"?

I went to the doctor yesterday because I was bleeding, but it wasn't my period. I guess I should have asked but I forgot to, so can I? It's really REALLY heavy. Like a heavy period. and it's coming out in blobs. I'm going to school and I have to wear khaki pants and if blood gets on them I will be so mortified. Panty liners are WAY too small and pads will have me sitting in a pile of blood goo by the time 1st period is over. can I safely wear a tampon?