Missing a dose or two of Augmentin 625 and extending the course to 7 days will not cause any harm - that is a standard duration for a jaw/dental space infection anyway. What matters is that you do not stop early and that the lump is actually shrinking. If the swelling is the same or bigger after 7 days, or you get fever, trismus or difficulty swallowing, it is likely a dental focus or an abscess that needs drainage, not more antibiotics. Loose stools or thrush with clavulanate are common - take it after food, add curd or a probiotic.
Next Steps
Finish the full 7 days as advised, take it after food, and get the lump examined once the course ends. Get a dental check for the same side tooth. If it is not settling, book a consult with me on Practo or at Synergy Multispeciality Hospital, Miraj.