try different servers.
I would follow pulchr's advice.
i need to ask something to to help u...well i hope so. have u changed/edited ur cl_maxpackets,/rate,packetdup, etc if u have restore them back to normal i had the same problem as u a long time ago try restroring them back see if that helps at all
if it doesen't then just play on unlagged servers or servers with low ping.
hope this all helps!
P.S:Wat country u in? if u live in aussie i could give u a list of servers with descent ping
P.M Me