Can I take antibiotics or over-the-counter anti-diarrheal drug for an e. Coli infection?

Yes. The strains of e.Coli that cause travelers diarrhea can be treated with the antibiotics Cipro (ciprofloxacin) or rifaximin. Antidiarrheal can be taken for symptoms. In the past there was some concern that antidiarrheals would prolong the infection, but that does not seem to be the case.
No. Otc anti-diarrheal drugs and antibiotics do not help for e. Coli related gastroenteritis, and if anything might keep you sick longer. Grin and bear it, and keep your fluids up to combat this infection.