I would not give Tylenol. If it is a sprain or strain any pain will limit his movement and enable it to heal better. Masking it, just encourages them to injure themselves further, when they are already still active. He is clearly not overly concerned about it from that video so a painkiller is totally unnecessary in my opinion. Limiting his ranging might benefit it if it is a strain but if it is Marek's, it may stress him and make it worse. I would just continue as you are now since he doesn't appear to be overly unhappy. We cannot be sure what is wrong so it seems unreasonable to set a time scale for it healing or consider medicating it. If he was in serious pain, he would be immobilising himself (standing around in a corner somewhere) and possibly going off his food and just looking sick. I'm not seeing any of that in the video.