Is my son just teething?

5 month old son has been fine for a while crying sometimes because he is tired but cant sleep because he is teething. last night he wouldnt settle he was crying and then started screaing at the top of his voice and only stopped when i stood up with him and rocked him.. he was so tired he couldnt keep his eyes open.. and then again he did the same this morning.. he only usually cried for 15 to 20mins but he cries like hes been hurt