The given sentence indicates an action that has happened till the time the sentence was written: 'You have been suffering...'
The present perfect tense expresses an action that has just completed or is relevant till date.
Hence, the given sentence will be in present perfect tense.
Option B: 'Haven't been able to' is in the present perfect tense, where 'haven't' is the contraction of 'have not'.
('Have (not) been' follows the present perfect syntax 'have + past participle (been)', where the given sentence is in the negative 'have not'.)
Hence option B is correct.
Option A: 'Was not able to' indicates an action that happened in the past, with no connection to the present. 'Was' indicates the simple past tense and does not agree with the tense of the sentence.
Option C: 'Won't be' indicates a future action that has not yet happened, whereas the sentence indicates an action that has just happened.
Option D: 'Am not able to' states a present action, that happens on a daily basis or a general truth.
But, the word 'recently' suggests that the action has started in the past and is still relevant in the present, i.e., the present perfect tense. So, the simple present 'am not' is not appropriate.
Hence options A, C and D are incorrect.