7 month old always whinging

Li

My little boy hasn’t ever been the happiest smiliest baby but he’s met all his milestones and I know how to get a smile or laugh out of him but recently he seems to whine all day long. Is it just that he’s starting to crawl and getting frustrated maybe? He never seems content just to sit and play and I’m worried I’m missing something. Obvs my first baby so I’ve no experience to pull from, any advice would be great.