How can I manage chronic idiopathic constipation?

Hello doctor,

I am a 69-year-old male with 74 kg weight (constant for 45 years), 174 cm height, BMI 24 and non-diabetic. My blood pressure is under control, i.e., 130/70 mmHg with Temsan 40 mg one tablet a day and Metolar 25 two tablets a day. CBC, urea, creatinine, urine reports are all normal. Chest X-ray is normal along with ECG. I am suffering from chronic idiopathic constipation from the past 12 years. I have managed my constipation with fiber supplements, ayurvedic medicines, regular walk (8 km every day), good diet with fruits, etc., in the past. However, two years back, I had sinusitis and was given a heavy dose of antibiotics Cefuroxime Axetil 500 mg two tablets a day for 10 days. This heavy dose completely disturbed my motion, and I have not been able to pass stool normally for last 15 months even with fiber supplements and ayurvedic medicines. To overcome this, I have taken following medicines prescribed by the doctor:

1. Lactifiber two to three spoons at night in warm water.
2. Pegred 2 spoons at night.
3. PEG fiber powder three tablespoons at night.
4. Ganaton Total.
5. Pruvict 2 mg (Prucalopride).

Above medicines were not at all helpful. Then, I was prescribed with the following:

1. Tablet Cremalax one tablet at night.
2. Pruvict 2 mg at lunch.
3. Syrup Lactihep 3 tablespoons before bed.
4. Movical sachet at night with glass of water.

The above combination worked like a miracle. I thought that my constipation problem is solved once for all. However, the effect lasted only for 4 to 5 days, and my system is back to abnormal. Currently, I am managing my constipation with tap water enema which I inject through the anus and wait for 5 to 10 minutes for the pressure to get generated and relieved. This allows emptying my bowl very well with great relief and a good appetite. I was in abroad for four months and has gained weight of around 3 kg. I walk every day around 6 to 8 km and do yoga to strengthen belly muscles. My fasting sugar was 65 mg/dl two weeks back. There is no fatigue. I have a good sleep during day and night, and currently, I take Shelcal 500 one tablet a day. Please let me know what course of action comes to your mind.