I wouldn’t go as far as “massively” – my mother had moderate elephantiasis in the last years of her life, so I know what that looks like, and this isn’t anywhere near as bad. I have swelling around the top of the ankles and on the instep – combined, enough to make getting shoes on very difficult. I have a naturally high instep anyway, which makes it hard enough to find comfortable shoes. I’ve also had some slight swelling of the left calf – enough to make a noticeable difference in the tightness of the two trouser legs. My consultant has said it’s a predictable side-effect of steroids (Dexamethasone 20mg, two days of each week), and that matches many online sources. I’m now taking a low-strength diuretic Furosamide 40mg which is having a slight effect, but I’ve not been on it long. I don’t believe that it’s a direct result of myeloma.
The main thing is to spend as much time as possible with legs elevated at, or preferably above, heart level – which is difficult while also trying to live a reasonably normal life. My feet, for instance, are on the floor right now…
Until I started the diuretic I found that on getting up in the morning, the swelling was down by 50% or so. The last few days, it’s been down close to 100% – but it comes back within an hour or so. I haven’t yet tried sleeping with a pillow or something to raise my legs higher – I have trouble enough sleeping because of the dex – so I’m keeping that one in reserve for the time being. Sounds to me as if maybe you should give it a try.