Possible causes of limb swelling?

Before I ask, I am not looking for a diagnosis. I'm only asking for possibilities of what this could be. Could anyone give me any possibilities as to why I experience limb swelling? Whether it's my levels of something being off, an autoimmune disease, or some other condition, any suggested possibility is appreciated. I have been experiencing episodes of limb swelling for 5–6 years. Sometimes, both my arms and legs swell up. Sometimes, it's only my legs or arms. Sometimes, it's only one of my arms or legs. It's pretty inconsistent. I have had times where I had two flare ups in a week, and, occasionally, I can go a month or two without anything happening. The swelling isn't really bad, and when just looking at it, it seems completely normal. I'm not bedridden or in complete agony when it happens, but it is painful and makes getting around and doing things harder. It typically lasts at least half a day. The longest it lasted for was around a day and a half. I haven't found any patterns for when it happens. Info: •18 (about to be 19) •Female