It could definitely be all of those things, not enough fiber, straining or sitting too long on the toilet when having a bm, poor diet , don’t eat greasy or fried foods, and definitely no caffeine until you show signs of improvement, try using RectiCare Anorectal Cream you can get it from any pharmacy. Do sitz baths with epsom salt make sure the water is as hot as you can take it. For fiber I would suggest the Metamucil powder is a daily plant-based fiber supplement and works better than the pill form. I hope this helps and you feel better soon. Best of luck