You are right regarding the fact that Imipram causes gait disturbances due to its central effect. But it is dose dependent & occurs on prolonged intake of the drug.
So, the symptoms as mentioned in your case may not be attributed entirely to the side effects of Imipram.
In your post, you have not mentioned about any history of Hypertension
, Diabetes, Hypo/ Hyperthyroidism
Under such circumstances, you need to undergo certain investigations like estimation of blood pressure & blood sugar values, complete blood count
, serum electrolyte assay & electromyography
to detect any pathological cause for your symptoms.