Many cockerels tend to get testy about the time they're getting ready to breed. Teenage male hormones. At this stage, they may have more hormones, than good sense. Most of the time when you catch this behavior early, it can be corrected, but it begins with your behavior. First off, I'm going to suggest a "rooster stick". The purpose of this is NOT to beat the stew out of the cockerel. It extends your reach, and can be used to gently, but firmly pop him on the butt when needed. It can be anything from a plastic kid's bat, to a yardstick, or the equivalent.
The next time you walk into your pen/coop have your rooster stick handy. Walk straight up to the offending cockerel/rooster. Going straight to the coop chores, without addressing him first, tells him he is in charge. If he stands there, gently pop his butt, and get him moving out of your way. Keep him moving away from you for a minute or two. Stop and look at his posture. Is all his weight on one leg? Is he giving you stink eye? Get him moving again for another minute or two. Now put fresh water, then feed. When you put in the feed, allow all the females to eat, but tamp the rooster stick, or gently pop his butt to get him away from the food. At first the females may be startled, or scoff, but they will get over it quickly. After the females have eaten a little, and he's staying away, back up a little, and let him have a little food. After a couple bites of food, approach him. If he doesn't move, tap his butt. Make him move. Now, turn to leave the coop. Watch out of the corner of your eye that he doesn't come towards you, but don't actually back out, or turn your head to watch your back as you leave. If he starts after you, turn and approach him, popping him on the butt, until he moves out of your way.
Repeat this every day for at least a week. It sounds like a lot, but in practice, it will only take a couple more minutes of your time. By the end of the week, you should be able to enter the run/coop area, and he will automatically begin moving out of your way. When he gets out of your way, and comes to a stop, his posture should be standing on both legs, and him engaging in normal activities, like looking for food on the ground. This is what you want. You should be able to move freely about the coop, around the females, and him keep some distance. When he's at this stage, every few days, reach down, grab him, pick him up, and check him over. Then put him back down, and he should put some distance between you, then resume normal chicken activities. Usually with young ones, within a week to 10 days, you can get them under control. At that point, I don't even use the rooster stick, but I never enter any of my run/coops without heading straight to the alpha rooster, and get him moving out of my way, then head over to do coop chores.
