Mine do that occasionally aswell. But it dosent sound as if the tank is crowded. What I do is i add a little bit of stress coat around the area where the fish is evemtually they calm down. If I have one that dosent calm down i set it in my net breeder so they get a little time alone after about a half hour they chill out.
Cripp, if this is a new or fairly new tank, try a large water change using a dechlorinator for the water. The laying on the bottom after some frantic activity sounds like a water quality problem to me.