Bicycle Mechanics - BB and shifter problems

I was riding the other day and towards the end of the ride for no apparent reason when ever I tried to press down on the left side crank I wasn't able to push it down. It felt like it was caught on something metal and it sounded that way too. I would back pedal a little and it would go away. I have no idea what the problem was. It would do this every so often with no apparent reason. Also, around the same time I was having trouble downshifting into the larger cogs. I could get as low as third gear but after that I was not physically able to press the thumb shifter in to downshift further. The trigger shifter to upshift into the smaller cogs worked perfectly. Any ideas on either probelm would be appreciated.

First guess is chain suck due to a damaged chainring, possibly bent teeth. Inspect your chainrings carefully.

Other possibilities: debris in your cassette or a bent rear derailluer.

Derailleur may have been banged which would result in needing to readjust the limit screws or unbending it.

The cable may have rusted or become seized.

It can be a number of things.

Tried to work on it today. Didn't have any trouble getting the pedals around but had some trouble up shifting now. Played with the screws and everything but no luck. I'm gonna take it to the LBS tomorrow to see what's wrong with it. All the teeth looked ok on all the gears, but I could be wrong. It was weird how everything suddenly started for no apparent reason. I was on flat trail when it all started.

Gotta love bikes!

Picked up the ride today. Got a new shifter cable out of it. The guy was also nice enough to readjust and lube everything for me too.