Salamualaikum.
Yes. Ive been throu those hard phases. It was started in 2005, I was doing Taraweh and suddenly the thougts came out of the blue. I was trembled, I was scared to death, and I felt alone, I said to my self that it was impossible for me to tell this to everyone as I was afraid they would think Im crazY! doh...
It disappeared after I spent so many naights crying and begging.
Last few weeks, the thoughts came again even stronger, such an ironic, I had those blasphemy when I was in Majlis Dzikr, I was trembled and fallen to pieces, I thought I was a munafiqun who have "illnesses in their heart", but thats not the case. I browsed in the internet relating to my symptoms, and apparently I have this Obsessive unwanted thoughts. it is close to OCD.
I couldnt sleep, I didnt go to work, I hardly did anything. How could I eat, work, sleep while my Iman is damage? But insha Allah, that is not the case. It is a test. I kept searching in the internet ... but they didnt satisfy me,
I was longing for islamic explanations, subhanallah, I have found it.
It is waswas.
And the idea how you overcome with such unwanted and disturbing thoughts, you may find them in this forum, check again, many good people have explain, esp those who have been throu this.
The stronger your fear is, the stronger the thoughts have the power.. when you are less fear, the thoughts will be weaker insha Allah. but its easy to say, yes indeed, but nothing is impossible for Allah. down on your knee and pray, cry

, beg, I used to mention in details what I felt in my prayer, my fear, anxious, my worries, and come up with blasphemious thoughts and I seeked refugee, forgiveness and power to cope with these thoughts, and
tears in prayers really help a lot, that surely helps insha Allah.
And one thing for sure, Shodaqoh-to needy people, to the closest relatives, to donate to your nearest Mosque, they will insha Allah fasten your prayer. Wallahu alam bishawab
A friend said to me (and she has decent knowledge in Islam), it is a good sign, the tests insha Allah will bring you to higher Maqom. I asked to a Ulama, Hasan Shahab, and he said it is relatively normal.
"And We will most certainly try you with somewhat of FEAR and hunger and loss of property and lives and fruits; and give good news to the patient," (Al Baqoroh - 155).