Dont worry your problem doesnt seem to be that bad
Usually falling on a beach and falling on road with an outstretched hand has diffefent outcomes and prognosis.... fortunately yours is former and hence no need to worry much...Now these scenarios are possible either you have pulled a muscle in your Rotator cuff (shoulder) or either of their tendons must have inflamed (tendonitis).
Which shoulder movement is causing the maximum pain??
Usually in such a scenario... OTC painkillers along with 5 sessions of TENS and Pulsed Ultrasound coupled with Anti inflammatory gel is the best solution to get your shoulder pain to decrease dramatically after which overhead shoulder movements should be commenced.