[borrachopower]

all the problems listed above would be part of the differential diagnosis for any Dr.
also, orthopedic tests help, but do not establish a full diagnosis.
plain film will probably not reveal anything....MRI is what is needed as the bro's above suggested.
ACL injuries most commonly occur when there is anterior translation of the tibia but can occur during twisting.
Initially, the symptoms are pain, and fairly immediate swelling. Often patients will complain of hearing a loud POP, which is the sound of the actual ligament tearing.

Usually after the pain and swelling resolve, patients complain of episodes of instability, or giving-way. The knee feels loose. Some people liken this to walking on rollerskates
rules in orthopedics-pain is good, means ligament is still intact(1st-2nd degree sprain)

no pain during orthopedic tests-bad sign, probably means complete tear(3rd degree)

see your Dr bro.......