I think the first question you need to answer for yourself is whether or not what you are experiencing is actually cramping (versus a more serious injury). You said you've been experiencing pain since summer of 2017, which makes me think it's not just usual cramping that comes along with running. Another reason I am skeptical to say this is cramping is because it is happening in your legs. Usually, cramps from running occur around your midsection. And the fact that you took some time off from running but still experienced pain when you returned is another red flag.
Think back to July - do you remember hurting yourself at all? Perhaps you did something that, at the time, seemed quite minimal but caused a bit of pain. And what kind of "cramping" do you mean? What is the pain like? I.e. is it a burning pain? A dull pain or a sharp, stabbing pain? Can you put any weight on it at all without it hurting? Is it fine when you are performing other methods of exercise or weight-bearing activities? I know you say you don't want to see a specialist, but I honestly think that's the first step to heal.
If it IS in fact leg cramps, well then you're not alone! Leg cramps typically occur in the calves, quads, or hamstrings and are commonly called "Charley Horses." One of the tell-tale signs of leg cramps is waking up in the middle of the night from them. And they can be oh-so-painful! The most common form of all cramping is dehydration, so start paying attention to your water intake throughout the day and make sure you are getting more than enough in to stay nourished and hydrated through your runs. Pay close attention to your diet as well, and make sure you are getting balanced amounts of electrolytes, vitamins, and minerals, as well as fueling your body properly. Stretching is big, too. It can be an annoyance, but it helps improve circulation and loosen up those tight muscles, which is why they spaz out and cramp up in the first place. Properly warming up and cooling down after each run is beneficial as well.