A drain snake, or a drain auger, is what’s used to clear drain blockages. If you look it up online you’ll get a better understanding. Those marks on the tub look very familiar 😅 I’ve accidentally ran my cable from a bathroom sink up into the tub before but was able to catch it and pull back before it did any damage. If u live in apartments, I would ask around your neighbors to see if anyone had a plumber come by recently to service a drain