Ankle (possible Soleus) exercise Induced muscle cramp/bumps/pain

For almost a year now I've been getting what seemed like random bouts of cramp in the soleus region of my calf. It can be induced simply from a 5 minute walk to the shops, but upon a short rest it's usually relieved.

Im not an endurance athlete, but have recently started to train for a long trek event in Summer. During a slow jog, within 5-10 minutes my ankles begin to give me alot of pain, similar to cramp but I can still perform. The muscle goes very tight, and results in me having to stop shortly afterwards. Relief is not immediate (like when walking) and is sometimes so severe (after ~30mins f running), temporarily even walking/standing becomes painful.

Another strange thing of interest, is the swelling of small lumps which develop under the skin forming a collection of hard bumps. Within 10-20 minutes these go down and the pain reduces.

I've done a small amount of internet research and it seems like it could be numerous things: DHEA/Potassium imbalances; Induced compartment syndrome; Creatine induced muscle cramps (I ingest creatine as part of my resistance training); Varicose Veins etc. But none seem to really hit the nail on the head.

Any advice would be greatly appreciated. It is very difficult to train for a CV event when my ankles give out way before my CV system is even challenged!