This will get you a list of the sessions running, including the one you use to run the query.

select r.session_id,

r.blocking_session_id,

r.total_elapsed_time,

r.reads,

r.logical_reads,

s.host_name,

s.login_name,

p.query_plan,

db_name(r.database_id)

from sys.dm_exec_requests r

inner join sys.dm_exec_sessions s ON s.session_id = r.session_id

cross apply sys.dm_exec_sql_text(r.sql_handle) t

cross apply sys.dm_exec_query_plan(plan_handle) p

order by r.total_elapsed_time desc;

However, it sounds like you have a pretty serious performance problem, so I would start by reading the articles that Gail provided. Performance problems generally build up over time unless you've had a recent release that caused something serious. You're going to need to get to the bottom of it and fix the root cause of the problem.