Is it possible to trunk two 2950 switches? I can trunk one of the 2950 to a 3650 with no problem. When I try and trunk a 2950 with another 2950....That's a no go....
Well it sound like you had physical layer problems (no link)
Possibly the gigabit interfaces were different (SX vs LX), or you had some kind of fiber problem (impossible to tell without testing it with a scanner)