There are so many things to unpack and I'm not very elegant and honestly I'm pretty brutal usually when I discuss my own weight so there's a chance I could offend you and if I do please know that's not my intention.
I took a couple of guesses and assumed you are a 30 year old female and chucked that into a BMI calculator.
Healthy weight range for your height:
8st 10lb - 11st 11lb
You're carrying an entire extra person and that is why you're struggling. One of the biggest things I've learned recently is that mentally I think I am considerably more capable than I really am. I've been setting goals which sound fantastic on paper but my body isn't ready for it.
I have a similar pain nearby my right calf muscle and it's probably caused by pushing too hard. It's humbling to fail when you know other people could do better.
This is where I think you're being very wise and reaching out to people on the forum, it's been a valuable thing for me, as a reality check it's essential.
Frankly you are going to suffer for a while, for me personally, I had to endure days of excruciating muscle pain where I was tearing the muscles and rebuilding them from my walks. I couldn't walk up and down the stairs without holding on and whimpering quietly as I was sore again from a recent walk.
Once those particular pains went away more subtle screams could be heard from other areas of my body.
Joint pain in my ankles especially being the most concerning.
Keeping in mind prior to all of this I walked to the shop every morning at 7am for about a year alongside eating healthily (read: correctly not binging or starving). That short distance every day felt good and my body was handling it perfectly. So I had an okay-ish-for-a-really-fat-person foundation to start from and it has still been brutal at times, especially in the beginning, building up distance.
Can you get your [censored] into gear without relying on someone else to motivate you to get out? if so, ditch em for a while, you need to figure out what is safe for you to do. If you need that additional push to get out then I'm not sure how to handle the situation better but you need to focus on what is correct for you to do.
Something I wasn't sure about with what you said was that you mentioned walking then running and going for a run. I truly hope you're not trying to run or jog yet.
I recall one day I was out for a walk where I saw another fat man walking, as we crossed paths I noticed he was looking exhausted which I felt needed a comment from me to try and boost his morale. "Come on mate, youve got this!", i blurted out. We had a little chat which he explained he had already walked 15 miles that day. I was shocked and impressed and like I told him I was lucky to make 5 miles on a good day.
That conversation made me push harder beyond what my body was ready for and i started aiming for 10 miles in future walks and whilst I made large incremental jumps towards it I ultimately had to concede I'm not ready for it. I used to be able to walk 10 miles with no problem whatsoever too, I would walk along the same route as the northern line (london underground) on occasion for fun. So to accept that actually I'm going to need to build up slowly was impossible. It was causing me severe bouts of guilt and depression for failing to meet my high standards.
Until I finally took on board what people have been telling me here on the forum. It's great to push yourself, and even through soreness but you gotta be sensible about it. Now I go out more days a week but limit myself to much lower distances because it all adds up anyway in the long run. It's all far more enjoyable again now too.
I hope you continue to walk because I truly love it, when you take some of the guilt and pressure away, it becomes beautiful.