I Got Red Coloured Stretch Marks In My Lower Abdomen Skin

i am in my 9 months of pregnancy . since 7th and 8th months I got red coloured stretch marks in my lower abdomen skin . Though I know it is natural in pregnancy, but i am having itches and sometimes its very severe when i return from walk, i sweat and itching starts in the marking areas. its unable to control from scratching. last few days I am seeing it has got more red and got tiny bumps. It looks scary when i saw it in mirror. how do i get rid of itching? i am using a lotion called Calapure which my doctor prescribed. i use it 3 times, then my grand told me to apply coconut oil. so when i feel itchy i use the coconut oil, and after some time i feel relief. but it again reappears. what to do ? its just killing me getting me crazy.