Thank you for the query.
The most common reason of your symptoms are destroyed intestinal bacteria due to antibiotics usage. Please note that almost every antibiotic affects good intestinal bacteria so the bad bacteria can colonize intestines. This can cause any mentioned by you symptoms including sore anus (due to hard stool and irritation of this area).
So I suggest you to start with probiotic
intake 3x1. If it wont normalize your bowels in few days, please visit your doctor and have stool tests done. If nothing will be found, colonoscopy
should be next.
Hope this will help.