In the middle of the muscle belly? Any brusing? Any appearance of asymetrical shallow indentation on the forearm and possibly "bulge" at the proximal or distal portion...?
Did it happen when doing eccentric motion or a rebound concentric motion during an eccentric motion?
What motion can you not do at this time? Wrist/finger flexion, forearm supination/pronation, or elbow/shoulder flexion...?
Any numbness, tinggling, pins and needles, and burning?
A "pop" can be anything from a complete muscle tear to just a joint over pressured into end range (like your knockles.)
There are so many structures in the forearm, fomr the finger/wrist flxors, forearm pronators, elbow flexors, the 3 joints of the elbow (yes the elbos is actually 3 articulating joints, not 1) that I cannot give you any recommendations unless it is examined in person.
What concerns me is that if you had a complete rupture of a muscle... A complete tear, throgh the accounts of many patients I have seen, can be painful or just felt like a twinge when it happend... A long muscle such as a bicep, when completely ruptured, has to be repaired from 48 hours up to a month (smaller and shorter ones suchs as the rotator cufss can wait a few months)... After that, since the muscle is detached and now rolled into a ball, the muscle fibers will become less elastic from being infiltrated with fat and fiber over time, and surgeons will NOT be able to re-attache it... And that means irreverisble compensatory motion.
It does not mean you have a rupture muscle fiber or even a complete one. But you should get it checked out AS SOON AS POSSIBLE since it hsa been a few months...