I have just started walking a little bit again with the help of crutches and braces after 5 years in a wheelchair but my calfs and knees are extremely tight and hurt after just a few minutes of walking. My doctor and trainer suggested stretching my calves but didn't really give many suggestions as to how. I still don't have much movement in my legs without assistance and could use some suggestions as to the best way to keep them loose so that they don't knot up and keep me from straightening my legs all the way.
Most calf exercises involve tip toeing. This Articles does a good summary of the description
If you are hurt more on land, you should find a swimming pool to do the walking exercises. You can start on the shallow side. Once comfortable, go the the deep end and walk without touching your feet much or not at all depending on depth. Still tip toeing though. You can walk at depth just enough to keep your head above, but full body under to allow more pressure exerted on you. Then as you get better, get to the depth where you are fully beneath, do tiptoe jumps so that you push your head out for a breath with each step. If you're not comfortable with deep water, you can buy a foam buoyancy belt that will keep you afloat but allow you the movement. Some public pools in the US even have buoyancy belts you can borrow. The pools that have water aerobics classes often have a whole bunch of them for the classes that can be borrowed when classes are not in session.
I highly recommend the pool exercises as the water adds overall pressure but also lessen the type of sharp pressure you get on land.
Short of this, use a few pain reliving patches such as the type from Japan (green and white box) while you use the steps to do calf raises. These will help lessen the pain for you and allow you to get through your "phase one." Use them sparingly and stop as soon as you're more comfortable.