Shoulder has many conditions in which movement gets difficult... Need to diagnose first

In shoulder impingement your rang of motion of shoulder will not restricted. But if it's getting frozen then only its range will less so diagnosis should be very clear as for both treatment protocols are different. If impingement is there then go for Cold pack for 15min thrice or 4 times in a day followed by DFO Gel but if it's frozen shoulder then hot pack & mobility pendular exercises etc more plus manual manipulations are required by Physiotherapy.

Apply ice for 20mts, twice a day Mulligan's manual therapy (MWMS/PRP)gives great results

Hot Fomentation. Shoulder Isometrics Capsular stretching

Proper diagnosis must. Start physiotherapy treatment if any rotator cuff injury then take laser physiotherapy treatment

If u are not able to move your shoulder it May be frozen shoulder as well. https://m.youtube.com/watch?v=OR2rdJnw9z8 Try doing these exercises.

Kindly give a clearer view on how did the pain and stiffnes start. Did you check with an orthopaedician or physiotherapist about impingement and rotator cuff injury? Amy history of fall or trauma on shoulder? The stiffnes and pain is treatable if u visit a good physiotherapist and follow the advices.

History of incidence can give a clarity that what happend exactly, if by chance happend without any specific reason, don't move your hand and don't check frequently, that might cause further damage and pain. Better apply ice or hot water fermentation. If it is have any specific reason like injury or fall......

It's good you have seen something on you tube , In both condition the ultimate treatment is regain strength with range without any Impinge at ac joint. So frist you meet physiotherapist to assess your problem .

Apply ice for pain relief Don't try to do any exercises on your own

How are you sure you have impingement or rotator cuff injury? Did you hurt yourself? Or lift something heavy overhead? Please get an XRay or MRI done and meet a physiotherapist.